Overshot



July 22, 1930. J. c. sToKEs 1,771,066

OVERSHOT Filed June ll, 1929 Patented Julyl 22, l1930 .man c. sroxns, or Hous'roN, TEXAS, AssIGNoR 'ro PATsN'r Ioiu-lcisz REED ROLLER BIT COMPANY, OF

HOUSTON, TEXAS, A CORPORATION OF TEXAS OVERSHOT Application led June 11, 1929. Serial No. 869,891.

This invention relates to deep well drilling apparatus and more particularly to overshots of that general type disclosed by my Letters PatentI ofthe United States No. 1,442,188, of January 16th, 1923.

The overshotprovided by the present invention is particularly adapted to remove from a. drill stem collapsible bit carriers or core barrels, but may also be used to remove other devices provided with means adapted to be engaged thereby.

The conventional collapsible bit carrier is providedwith aconical head, and the conventional overshot with a pair of pivoted dogs. The carrier is usually dropped into the drill stem and descends tothe lower end thereof to support the collapsible blades in their expanded positions. When it is desired to remove the carrier to mount new blades therein, the overshot is lowered into the drill stem by means of a suitable, cable until the pivoted dogs engage the conical head, after which the overshot and carrier connected thereto may be removed from the drill stem.

At times the carrier or other device becomes jammed or stuck in the bit head, and when the overshot is made to engage the same and an excessive pull is exertedl on the cable, the

cable breaks, and theremoval oi' the carrier and overshot thereby left in the stem is a difiicult and expensive task.

This invention has for one of its objects the provision of a new and improved overshot adapted to positively grip the conical head of a carrier or the like, but to release it when more than a predetermined k resistance 1s offered to its removal.

Other objects of the invention will hereinafter appear.

In the accompanying drawings which are illustrative of the preferred embodiment ot' the invention, Fig. 1 is a sectional elevation of the overshot engaging the conical head oi' a bit carrier; Fig. 2, a fragmentary view similar to Fig. 1 illustrating the relative posltions of the overshot and the carrier immediately before they are locked together; Fig. 3, a fragmentary side elevation of the overshot; and Fig. 4, a horizontal section on the line 4-4 of Fig. 3.

The overshot is indicated generally at O and the carrier at C. The overshot comprises a substantially cylindrical bifurcated body the upper end lof which is provided with a screw threaded shank 1 whereby it may be attached to a suitable element to which the cable is attached. The sprin fingers 2 and 3 of the overshot are provide respectively, with internal arcuate fifanges 2a and 3. The upper sides 2"" and 3a of these flanges are slightly inclined downwardly and inwardly; and the lower sides 2a and 3a of which are greatly inclined upwardly and inwardly.

The grip of the spring fingers 2 and?) may be varied by the bolt 4.

The carrier C is provided with a head hav- ,ing a conical section 5, a cylindrical section 6 and a truste-conical section 7.

Assuming that the carrier 6 is in position in the lowermost end of the drill stem, and its removal is desired, the overshot O is attached to the end of a cable and lowered in the drill stem. The spring fingers 2 and 3 are forced apart by the entrance of the head of the carrier therebetween. The lower sides 2a and 3a of the iianges 2a and 3a move over the conical section 5 of the carrier so that the flanges 2a and 3a may pass over the cylindrical section whereupon the fingers 2 and 3 are permitted to move toward each other and the upper sides 2a and 3a ried into contact with tion 7 Under normal conditions, the overshot may be elevated by the cable and will bring the carrier with it. But if the carrier C is jammed or stuck in the drill stem and more than a predetermined pull is necessary to release it, when said pull is applied to the overshot, the upper sides 2" and 3a of the iianges 2a and 3a will move outwardly over the frustoconical section 7 thereby forcing the fingers apart so that the flanges 2*l and 3a may move over the cylindrical section 6; and the overshot will be thereby released from the carrier. Danger of breaking the usual cable is thus eliminated.

The overshot may then be removed from the stem and a stronger cable connected thereto. The bolt 4 may then be tightened to oii'er more of the anges are carthe frusto-conical secresistance to the separation of the fingers 2 and 3. The overshot may then be again lowered into the stem and made to engage. the head of the carrier in the manner descrlbed above. When an upward pull is exerted on the overshot, the resistance offered by the bolt 4 to the separation of the fingers 2 and 3, is suliicient to prevent outward movement of the sides 2a and 3 on the frusto-conical section 7 and so the carrier may be forcibly removed.

Or, if for any reason it is inadvisable to force the carrier out of the drill stem, the drill stem itself with the carrier therein may be removed from the hole after the release of the carrier by the overshot has indicated that the carrier is stuck in the stem.

Various uses of the overshot other than that herein described will occur to those skilled in the art, and no limitation in this respect is to be inferred; and various changes may be made in the preferred embodiment illustrated within the scope of the following claims.

I claim:

l. An overshot having a pair of spring fingers constructed to yieldably resist separation,said fingers having internal flanges, the upper sides of said flanges being inclined downwardly and inwardly.

2. An overshot having a pair of spring fingers constructed to yieldably resist separation, said fingers having internal flanges, the upper sides of said flanges being inclined downwardly7 and inwardly, and the lower sides of said flanges being inclined upwardly and inwardly.

3. An overshot having a pairof spring fingers constructed to yieldably resist separation, said fingers having internal arcuate flanges, the upper sides of said flanges being inclined downwardly and inwardly.

4. An overshot having a pair of spring fingers constructed to yieldably resist separation, said fingers having internal arcuate flanges, the upper sides of said flangcs being inclined downwardly and inwardly, and the lower sides of said flanges being inclined upwardly and inwardly.

5. An overshot having a pair of spring fingers constructed to yieldably resist separation and an adjustable bolt to vary the grip of said fingers.

6. An overshot having a pair of spring fingers constructed to yieldably resist separation, said fingers having internal flanges, the upper sides of said flanges being inclined downwardly and inwardly, and an adjustable bolt to vary the grip of said fingers.

7. An overshot having a pair of spring fingers constructed to yieldably resist separation, said fingers having internal arcuate flanges, the upper sides of said flanges being inclined downwardly and inwardly, and an adjustable bolt to Vary Athe grip of said lingers.

8. The combination with a device having a headpthe lower surface of said head being inclined upwardly and outwardly, of an overshot having a palr of sprlng fingers, said fingers having flanges to engage said head.

9. The combination with a device having a head, the lower surface of said head being inclined upwardly and outwardly, of an overshot having a pair of spring fingers, said fingers having flanges to engage said head, the upper sides of said flanges being inclined downwardly and inwardly.

10. The combination with a device having a headthe lower surface of said head being inclined upwardly and outwardly, of an overshot having a pair of spring fingers, said fingers having flanges to engage said head, the upper sides of said flanges being inclined downwardly and inwardly, and an adjustable bolt to vary the grip of said fingers.

ll. An overshot having a pair of spring fingers constructed to yieldably resist movement from their active positions, said fingers having gripping members, the upper sides of said members being inclined downwardly and inwardly.

12. An overshot having a pair of spring fingers constructed to yieldably resist move-A ment from their active positions, said fingers having gripping members, the upper sides of said members being inclined downwardly and inwardly, and an adjustable bolt to vary the said resistance of said fingers.

13. A device of the character described having a head, said head having a lower surface inclined upwardly and outwardly.

14. A device of the character described having a head, said head having a conical section and an inverted frusto-conical section.

15. A device of the character described having a head, said head having a conical section, an inverted frusto-conical section, .and an intermediate cylindrical section,- the diameters of said cylindrical section, the base of said conical section, and the base of said frusto-conical section being substantially equal.

In testimony whereof, I hereunto aflix my signature. Y

' JOHN C. STOKES. 

